The Author(s) 2018. This article is published with open access at www.chitkara.edu.in/publications.

ABSTRACT

In this work we study the annihilation of dark matter, considering it as a neutral particle with magnetic and/or electric moments not null. The calculation of the effective section of the process χχ gg → is made starting from a general form of coupling χχg in the framework of an extension of the Standard Model. We found, when taking into account an annihilation of DDM-antiDDM to monoenergetic photons, that for small masses, mχ ≤ 0 GeV, an electric dipole moment ~10–6 e cm is required to satisfy the current residual density, while for the range of greater sensitivity of HAWC, 10 TeV < Eg < 20 TeV, the electrical dipole moment must be of the order of 10–8 e cm.

INTRODUCTION

The enigma of dark matter is perhaps the most interesting problem of modern astrophysics, so much so that it has led to the incursion of elementary particle physics. The joint work of these two disciplines has as one of its main objectives to determine the nature and properties of dark matter, either through direct or indirect detection. This enigma of the missing mass has been a problem since Zwicky in 1933 measured the masses of extragalactic systems [1]. Nowadays, given the evidences of the galactic dynamics (rotation curves), galaxy clusters, structure formation, as well as the Big Bang’s nucleosynthesis and the cosmic background radiation, it is suggested that baryons can only explain matter, the majority of the missing mass must be non-baryonic. The non-baryonic nature of dark matter is clear evidence that our understanding of the matter components of elementary particle physics, beautifully described by the Standard Model (SM) is incomplete. For this reason, theoretical physicists have considered new physics beyond the Standard Model in order to accommodate (at least) a non-baryonic candidate as dark matter (DM), since the only dark matter candidate in the SM is the neutrino, which is inadequate to explain most of the DM [2]. The most promising candidates that emerge beyond the Standard Model, are the massive particles of weak interaction, commonly known as WIMPs, examples of these are the neutralino [3] and the axion [4], but unfortunately they have not been detected. In the absence of the discovery of such particles it is worth exploring other possibilities. An alternative line of research is to take an approach independent of the model and try to phenomenologically explore the possible properties of a dark matter particle. On this line, the restrictions for strongly interacting dark matter were considered in Ref. [5]. In addition, the autointeraction of dark matter has been considered in the Refs. [6,7]. Some people have studied whether dark matter could be charged [8] or have a milichargue [9,10]. Likewise, it has been studied that within these phenomenological possibilities, dark matter has an electric or magnetic dipole moment [11, 12, 13-15]. In this work we consider, precisely, the possibility that dark matter possesses an electrical and/or magnetic dipole moment and can emit gamma radiation as a result of its annihilation. In the next section, we introduce the effective Lagrangian for the interaction of dipolar dark matter with photons. The calculation of the annihilation cross-section by the thermally averaged relative velocity is calculated in section 3.In section 4 we speak of monoenergetic gamma radiation, while in section 5 conditions are established on the magnetic and electric dipole moment to satisfy the current residual abundance. We give our conclusions in section 6.